Variable-resistance unit.



B. F. WILLISTON.

VARI'ABLE RESISTANCE UNIT.

APPLICATION FILED MAY 11. 1916.

1,226,837. Patented May 22, 1917.

. UNITED STATES PATENT OFFICE.

- BENJAMIN F. WILLISTON, OF DETROIT, MICHIGAN, ASSIGNOR F ONE-HALF TO RUFUS E. GREEN,-OF DETROIT, MICHIGAN.

VARIABLE-RESISTANCE UNIT.

Specification of Letters Patent.

Patented May 22, 1917.

Application filed May 17, 1916. Serial No. 98,001.

- To all whom it may concern:

Be it known that I, BENJAMIN F. WILLIS- TON, a citizen of the United States, and a resident of Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Variable-Resistance Units; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being bad to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

This invention relates to improvements in resistance units for electric current conductors and it consists of the matters hereinafter described and more particularly pointed out in the appended claims.

One of the objectsof the invention is to produce a simple and ellicient device of the kind described, capable of being manipulated so as to introduce into the circuit to which it is applied, any one of a plurality of difl'erent resistances, without materially disturbing or changing the normal positions of the line wires of said circuit. Another object is to so construct the device, that soldered joints are eliminated and that proper,

inspection of the unit may be made when in circuit without taking said unit apart.

Fig. 5 represents a transverse horizontal sectional view therethrough, the plane of the section being indicated by the line 55 of Fig. 4.

eferring now in detail to that embodiment of the invention illustrated in the drawings ;10 indicates a block of suitable insulating material, which constitutes the body of the improved resistance unit. Said body consists of a core 11 and of a disk-like head 12 which isof greater diameter than that of the core and projects beyond and overhangs the same. As shown the said head and core are cylindrical and the core provides the base of the resistance unit. A central hole 13 extends through the body and is adapted to receive a screw 14 by means of which the. unit may be attached to a fixed support 15, as illustrated in Fig. 4:.

The core 11 is provided with a pair of spaced, radial flanges namely a. flange 16 at the bottom and a flange l7 spaced somewhat below the head 12. The flange 17 is provided with a plurality of notches 17 Upon the body 12 between the flanges 16 and 17 is wound a resistance coil 18. 19 indicates a tubular sleeve of insulatingmaterial which fits snugly upon the flanges 16 and 17 and incloses and protects the resistance'coil.

symmetrically arranged upon the head 12 and fixed thereto are a plurality of upright binding posts (in this case four) 20, 21, 22 and 23 respectively. Said binding posts are disposed in the overhanging part ofthe head and between the notches 17? in the flange 17. As-all of said binding posts are similar in construction a detailed description of one (20) will suflice for all, the like superfixes indicating like parts throughout.

The binding post 20 comprises a headed bolt20' which extends through a hole in the head 12 and suitable washers 20"20 are placed on said bolt in a position engaging the opposite faces of said head. A jam nut 20 engages the washer 20 and secures said bolt in position. Mounted on said bolt next to the nut 20 is a pair of washers 20 between which one of the main line wires of the circuit in which the ,unit is interposed is adapted to be secured. A pair of lock nuts 20 are mounted on the bolt beyond said last named washers for holding said Washers clamped upon the line wire. On the head 12, between the several binding posts, are stamped or otherwise marked suitable numerals as 2, 3, 4 and 9 (see Fig. 2) which indicate the number of fractional units of resistance, in this case tenths of ohms, to be obtained by connecting the binding posts on each side of a numeral, in the circuit.

The resistance wire 18 is made of a single length and is wound and connected as follows: Starting with the binding post- 20,

one end of the resistance wire is looped about the bolt 20 and is engaged between the washer 20 and the bolt head. It is then engaged in the notch 17 in the flange 17 between the binding posts 20 and 21 and is then wound upon the core 11 to provide a coil 4 of a length to give a predetermined resistance. The wire is then brought back through the same notch 17 and is looped about the bolt 21 21, and engaged between its head and the associated washer. The -wire is then engaged in the next notch 17 and then wound upon the core to provide a resistance coil 3 of a shorter length and less resistance and is then brought back through the same notch and looped upon the next binding post 22. In a like manner a coil 2 of still less resistance is wound upon the core and connected between the binding posts 22 and 23, the end of the wire being attached to. the binding post 23. It will be noticed from Fig. 2 that the index numerals 4, 3 and 2 on the head are placed respectively between the binding posts 20 and 21, 21 and 22, and 22 and 23, thus indicating that a resistance equal to four tenths, three tenths or two tenths of an ohm may be interposed in the circuit when the line wires of the circuit, are connected to the corresponding binding posts. By connecting binding posts which are not adjacent, the sum of the resistances interposed between each of said binding posts and the intermediate binding post will be interposed in the circuit. Thus the resistance-:unit as illustrated herein provides for resistances 0.2, 0.3, 0.4, 0.5, 0.7, and 0.9 of an ohm. In addition, by the use of a jumper bar to bridge the posts 21 and 22 to cut out the coil 3, an additional resistance of 0.6 ohms may be obtained.

All of these variations in resistances may be obtained simply by rotating the block as a whole about the screw 14 as an axis thus bringing the two desired binding posts into proper relation with the line wires so that the desired connections may be readily made without disturbing or changing the line wire terminals.

As is apparent, my improved resistance unit is free from soldered connections found in resistance units as before produced, which have always been objectionable as the soldering flux produced corrosion of the wires with the usual attending breakage.

While in describing my invention I have referred to certain details of construction, form and arrangement, it will be understood that the invention is not to be limited thereto, except as may be pointed out in the appended claims.

I claim as my invention 1. A, resistance unit comprising, a body of insulating material having a core and a head overhanging said core, a plurality of bindof the next binding post ing posts fixed to said head, and a single length of resistance wire wound upon the core to provide a plurality of coils of different lengths, said wire being looped at intervals about said binding posts to connect each coil to the adjacent binding posts.

2. A resistance unit comprising, a body of insulating material having a core and a head overhanging said core, a plurality of binding posts fixed to said head, a single length o resistance wire wound upon the core to provide a plurality of coils of different lengths, said wire being looped at intervals about said binding posts to connect each coil to the adjacent binding posts, in combination with means for attaching said unit to a support, said means providing for rotative movement of the said unit about the axis of its core.

3. A resistance unit comprising a body of insulating material having a core and a head overhanging said core said core being provided with spaced radial flanges, a plurality of binding posts fixed to said head, a single length of resistance wire wound upon the core between the said flanges to provide a plurality of coils of different lengths, said wire being looped at intervals about said binding posts to connect each coil to the adjacent binding posts, and an insulating sleeve engaged upon said flanges and inclosing said coils.

4. A resistance unit' comprising a body of insulating material having a core and a head overhanging said core, said core being provided with spaced radial flanges, a plurality of binding posts fixed to said head, a single length of resistance wire wound upon the core between the said flanges to rovide a plurality of coils of diflt'erent lengt s, said wire being looped at intervals about said binding posts to connect each coil to the adjacentbinding posts, and means for attaching said unit to a support, said means providing for rotative movement of the unit about the axis of its core.

5. A resistance unit comprising a body of insulating material having a core and a head overhanging said core, said core being provided with a radial flange at the bottom and with a similar radial flange spaced some-- what below the head, a plurality of binding posts fixed to said head, a single length of resistance wire wound upon the core between the said flanges to provide a plurality of coils of different lengths, said wire being looped at intervals about said binding posts to connect each coil to the adjacent binding posts, and an insulating sleeve engaged upon said flangesand inclosing said coils.

6. A resistance unit comprising, a body of insulating material having a core and a head overhanging said core, a plurality of binding posts fixed to said head, a single length of resistance Wire wound to provide a plurality of coils of different lengths, said Wire presence of two Witnesses, this 10th day of being connected at intervals to said binding May A. D. 1916. posts to connect each coil to the associated binding posts, and insulating means sur- BENJAMIN WILLISTON' .5, rounding said coils and protecting them.- Witnesses:

In testimony that I claim the foregoing .1110. M. SEEALD, as my invention I aflix my signature in the GEO. J. MCNABB. 

